| 摘要 |
PURPOSE:To produce the titled base material having a small loss in a longer wavelength range by introducing a gaseous compound contg. Si and halogen into the gap between core and clad materials, heating the materials, and making them solid in a gaseous atmosphere contg. F. CONSTITUTION:A gas contg. F such as SF6 or CF4 is introduced into a pipe 12 for a clad having a lower refractive index than a core material 13 from a line 15, and the pipe 12 is heated to >=1,900 deg.C to remove impurities. The core material 13 made of a quartz glass rod is put in the pipe 12 and heated to 500-1,900 deg.C with a heating source 18 while a gaseous compound contg. Si and halogen such as SiCl4 or SiF4 is introduced from a line 15. The gas in the pipe 12 is then changed over to a gaseous mixture of a gas contg. F such as SF6 or NF3 with O2 and the pipe 12 is made solid by moving the heating source 18 along the rotating pipe 12. |
